Associating processor and processor core energy consumption with a task such as a virtual machine is disclosed. Various events cause a trace record to be written to a trace buffer for a processor. An identifier associated with a task using a processor core of the processor is read. In addition, one or more values associated with an energy consumption of the processor core are read. In response to the event, the one or more values associated with the energy consumption of the processor core and the identifier are written to the trace buffer memory.